When you misspelled a search query, Google's spell checker has always returned a single search suggestion, and shows a message(s) above the search results: "Showing results for [corrected query]. Search instead for [original query]".
Google has now started showing a "did you mean" message even for queries that are too ambiguous to be corrected automatically. The new feature is a clever way to combine spell checking with related searches and show additional suggestions for weird queries that are likely to be misspelled. Even if the suggestions aren't always useful, it's a low-risk feature and you won't see too often.
For example, if you search for [efrazin], a query that returns a small number of results, Google suggests four other similar keywords that are more popular, but the list doesn't include [e. frazin]: